adjusting temperature/pressure/volume
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adjusting temperature/pressure/volume
what is the best "guiding principle" for how to answer questions implying "Le Chatelier's Principle"/change in physical conditions? Will questions that ask about temperature always give whether or not the question is exothermic or endothermic?
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Re: adjusting temperature/pressure/volume
The best way is to identify the action that will counteract the change in the system.
Adding reactants will result in the production of products because that will result in some of the reactants being used up, and the ratio will be restored. The same applies to adding products; reactants will form so the ratio is restored.
If pressure increases/volume decreases, you want to decrease pressure by producing less moles.
If temperature increases, you want to decrease the temperature by using energy.
For questions involving temperature, either delta H will be given or it will be explicitly stated that the reaction is exothermic/endothermic.
Adding reactants will result in the production of products because that will result in some of the reactants being used up, and the ratio will be restored. The same applies to adding products; reactants will form so the ratio is restored.
If pressure increases/volume decreases, you want to decrease pressure by producing less moles.
If temperature increases, you want to decrease the temperature by using energy.
For questions involving temperature, either delta H will be given or it will be explicitly stated that the reaction is exothermic/endothermic.
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- Posts: 31
- Joined: Fri Sep 28, 2018 12:20 am
Re: adjusting temperature/pressure/volume
In cases such as a change in pressure you must consider the overall effect of the system. In the equation PV=nRT we can see that pressure and number of moles have a direct relationship. Thus an increase in pressure would increase the number of moles, the system would compensate by directing toward the side of the equations with less moles.
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